The field of the invention relates generally to detection of a binary state of a device and, more specifically, to systems and methods for determining a remote, non-powered verification of a binary state of a device.
At least some known systems read binary states of devices, such as an on-off state, an open-closed state, a high-low state, and/or a forward-reverse state, using one or more switches, transducers, and/or powered sensors. For example, on a rail freight car, a brake shoe is often applied to the wheel to facilitate decreasing the speed of the freight car as it travels. As the speed of the freight car increases, the temperature of the wheel increases, which may cause the brake to disengage which may result in an accident. Moreover, as the temperature of the wheel increases over time, the brake shoe may fail due to increased wear, thus increasing the operating costs of the railroad.
Accordingly, at least some known railroads monitor the temperature of the wheel and/or brake shoe. More specifically, at least some known monitoring systems employ a “hotbox detector” that uses an infrared detector to measure the temperature of the wheel. Moreover, the monitoring system alerts the train crew if the wheel temperature exceeds a predetermined temperature. However, such systems merely detect a symptom (for example, the increased temperature of the wheel) rather than the cause (for example, the continuously applied brake). As a result, often additional systems are necessary to determine a status of a device being monitored, such as a brake.